Yeah, the motherboards only support basic RAID, and are generally not very good quality - the main reason for implementing it is to give you 8 IDE devices instead of 4 connectable as standard. (Note, only 4 of the 8 devices can be set up for RAID)

If you're looking for speed alone, there's little point in going for RAID 5, which includes redundancy as well. You'll get optimum performance (at least on low-cost RAID cards) using what's known as RAID 0, which is simple disk striping, where a file is stored across more than one disk and so can be read from two (or more) disks simultaneously.

The motherboard options you have are:

RAID 0, which is up to 4 disks of striping, giving you theoretically 4 times the performance of a single drive (although realistically nothing near this). RAID 0 has no redundancy - any failure will mean virtually all data is lost. In this system, you get the full storage capacity (4 times the single disk size)

RAID 1, which is up to 4 disks of mirroring, gives you only the storage capacity of the smallest disk installed. Each file is written to all the disks at once, potentially allowing up to three failures (if you have 4 drives in this format) before any data loss. A decent RAID 1 system will allow you to swap in a new disk, and will then rebuild this disk so you retain maximum fault tolerance.

A RAID 0+1 system is, as it suggests, a combination of the two - in this case, 4 drives, with files striped (see RAID 0) across two disks, and mirrored across the other two. This gives you up to twice the performance of a single drive (again, theoretically), whilst meaning you can have up to 2 disk failures (although not any two, either the two main or the two backup disks) before data loss. In this case, you get twice the capacity of a single disk, or half the capacity of the total system, available for use.

If you want to stick with the Mobo RAID support, and have faster file access plus some redundancy, RAID 0+1 is probably the way to go - however, you do need 4 disks, preferably all the same size, to go down this route.

As you've gathered, this setup is cheaper in interface cost than a dedicated RAID controller, but more expensive in disk storage terms - with a RAID 5 controller, you could use the 4 disks in your RAID 0+1 system, to get 3 times the single disk size, up to 3 times transfer speed of a single disk, and still have the ability for any disk to fail.

HTH,

A.

*edit: gah, beaten to it!*